Coach Peter Laviolette was surprisingly calm after the Flyers’ biggest late-game meltdown in 24 years.

Maybe he was in a state of shock.

The Flyers blew third-period leads of 3-0 and 4-2 and lost in overtime to the Atlanta Thrashers, 5-4, before a stunned sellout crowd at the Wells Fargo Center on Saturday night.

It was the first time since 1987 the Flyers had lost after taking at least a three-goal lead into the third period. They lost to the Islanders on Nov. 21 of that year, 6-4, after taking a 4-1 lead into the third period.

Atlanta scored two goals in the final 2:59 of regulation to send the game into OT. The Flyers’ Kris Versteeg was in the penalty box for interference when the Thrashers cut it to 4-3, and the recently acquired winger committed a turnover that contributed to the tying goal, scored by Andrew Ladd with 45 seconds left and Atlanta’s goalie pulled for an extra skater.

Defenseman Ron Hainsey scored his third goal of the season, finishing a three-on-two break, to give Atlanta the win after 1:17 of the overtime.

“If you go back, look at it, and you break the game down, there was one scrambling part of the third period that I didn’t like where Bob (goalie Sergei Bobrovsky) had to make three or four saves in a row,” said Laviolette, whose team squandered Ville’s Leino’s first career hat trick. “The rest of it was in control. We had coverage and then something funny happened in the last couple minutes where we went to go get our goaltenders stick, we had possession of the puck, and then banked one on the side of the net.”

“There were a couple of funny bounces there at the end and a chain of events that were not right, but they kept coming,” he added. “They are a desperate hockey team that needs to win games in order to make the playoffs. They kept coming. You look back at this game and it is one of those tough ones to swallow. You feel like when it was 3-0, that the game should have ended 3-0.”

In their last 12 games, the Flyers have been outscored in the third period, 20-4, excluding empty-net goals.

“I don’t get the sense that we didn’t work in the third period. I think we did,” said Laviolette, referring to Saturday’s game. “The result is nauseating, but I think our guys competed in the third. This isn’t a Rangers game or an Edmonton game where we didn’t play well in the second and third. I think we competed but like I said, with the chain of events, nobody is going to sleep well with them.”

The Thrashers outscored the Flyers, 5-1, in the third period and overtime.

“Every time they got an opportunity, it was in the net,” Laviolette said.

Despite the loss, the Flyers actually gained ground. They picked up a point and moved three points ahead of Washington in the Eastern Conference, and they inched to five points ahead of Pittsburgh in the Atlantic Division.

The Flyers have a game in hand on both of those teams.

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BREAKAWAYS. Leino’s hat trick was the first by a Flyer on home ice since Mike Richards on Oct. 6, 2009 vs. Washington…..Jeff Carter is the only other Flyer with a hat trick this season….Laviolette gave the Flyers off on Sunday, their third day off in the last week……The Flyers managed just 24 shots, their third-lowest home total this season. Atlanta had 41 shots.....The Flyers were 2 for 2 on the power play, while Atlanta was 1 for 3.